1. Field of the Invention
The present invention relates to a portable electronic device having a display portion with a circuit composed of thin film transistors (hereinafter referred to as TFTs), for example, a portable electronic device equipped with a display device such as a liquid crystal display panel as the display portion.
Note that the portable electronic device in this specification means a portable information processing device in general, and includes a mobile telephone, a mobile television telephone, a portable computer, and the like.
2. Description of the Related Art
Conventionally, in a mobile telephone, one liquid crystal display device is normally used as the display portion. Further, because of a demand for miniaturization, there is a limitation to the size of the screen of the display portion.
Also, recently, the communication technology has progressed, and thus sending and receiving of electronic mails and access to home pages on the Internet can be made by using the mobile telephone.
Recently, although it is possible to send and receive of electronic mails by the mobile telephone, communication with only characters in a text form is possible. Thus, even when a message to which image data is attached by, for example, a personal computer or the like is received, the image data cannot be displayed on the display portion of the mobile telephone.
Also, even in the access to a home page on the Internet, image data on the home page cannot be displayed on the display portion of the mobile telephone.
Display of characters (text) or a simple image is sufficient in a display portion of a conventional mobile telephone. Thus, it is not necessary to use a high resolution display portion. Also, it is not necessary to use a full color display portion.
However, since it has been possible to communicate by electronic mails of the mobile telephone in recent years, a high resolution and full color display portion is greatly required. Among various mobile telephones, although a mobile telephone capable of displaying image data has been on sale, many mobile telephones have two-color display such as white and black. Thus, although there is the case where the full color display portion is used, image quality is low and it is difficult to see the image.
Also, when the image data is displayed on the display portion, the characters (text) cannot be displayed thereon. That is, the image data and the characters (text) cannot be simultaneously displayed.